Reduced colonic mucin degradation in breastfed infants colonized by subsp EVC001.

Mucin glycoproteins play an important role in protecting the gut epithelium by keeping gut microbes from direct contact with the gut epithelium while allowing for diffusion of small molecules from the lumen to the epithelium. The mucin glycocalyx can be degraded by gut bacteria such as and , but other bacteria, such as subsp, cannot consume mucin glycans. Untargeted mass spectrometry profiles were compared to microbiome profiles to assess how different gut microbiomes affect colonic mucin degradation. Samples obtained from nine infants colonized by EVC001 and from 10 infants colonized by higher levels of mucolytic taxa (controls), including , were compared. Previously performed untargeted nano-high-performance liquid chromatography-chip/time-of-flight mass spectrometry was used to detect and quantify glycans originating from colonic mucin. Colonic mucin-derived -glycans from control infants composed 37.68% (± 3.14% SD) of the total glycan structure pool, whereas colonic mucin-derived -glycans made up of only 1.78% (± 0.038% SD) of the total in EVC001 samples. The relative abundance of these colonic mucin-derived -glycans in the total glycan pool was higher among control, 26.98% (± 8.48% SD), relative to colonized infants, 1.68% (± 1.12% SD). Key taxa, such as , were significantly and positively correlated with the abundance of these structures, while were significantly and negatively associated with these structures. These results suggest that colonization of infants by may diminish colonic glycan degradation and help maintain barrier function in the gastrointestinal tract of infants.